in pre-poser 9, atmosphere only works with directional lites, not with glowing posersurface, not with point lites, not with IBL et al.  to separate aura from glowing sphere, modify edge-blend shader.  it would still go to zero at edge (normal to the camera) but it would also go to zero at centre, or some radius away from centre, e.g. using  torus rather than sphere as aura generator. YMMV.